WO2019100592A1 - Halogen-free flame retardant compound system for glass fiber reinforced nylon and application thereof in halogen-free flame retardant glass fiber reinforced nylon material - Google Patents

Abstract

Disclosed by the present invention is a halogen-free flame retardant compound system for glass fiber reinforced nylon, comprising the following raw material components according to weight percentage: 40-90% aluminum diethylphosphinate, 8-30% aluminum orthophosphite, 1-20% melamine metal phosphite and 1-10% zinc stannate. Disclosed by the present invention is a halogen-free flame retardant compound system for glass fiber reinforced nylon, the halogen-free flame retardant compound system having the characteristics of being highly flame retardant, being migration-free, and not corroding a device, thus overcoming the shortcomings of current aluminum diethylphosphinate-based phosphorus nitrogen compound flame retardant systems that are applied to glass fiber reinforced nylon materials; the compound system may be adapted well to a glass fiber reinforced nylon material system so as to obtain a halogen-free flame retardant glass fiber reinforced nylon material having excellent comprehensive performance.

Description

Halogen-free flame retardant compounding system for glass fiber reinforced nylon and its application in halogen-free flame retardant glass fiber reinforced nylon material Technical field

The invention relates to the technical field of flame retardants, in particular to a halogen-free flame retardant compounding system for glass fiber reinforced nylon and application thereof in a halogen-free flame-retardant glass fiber reinforced nylon material.

Background technique

Glass fiber reinforced nylon is widely used in the field of electronic appliances due to its good rigidity and impact resistance, low warpage, high dimensional stability, and good surface appearance. In these applications, flame retardant requirements are imposed on materials, and nylon is a flammable material. After being combined with glass fiber, glass fiber reinforced nylon is easier to burn due to the wicking effect of glass fiber. Therefore, when glass fiber reinforced nylon is applied in these fields, it is necessary to solve the problem of flame retardancy, and the presence of the wick effect makes it more difficult to flame retard.

At present, the flame retardancy of glass fiber reinforced nylon includes two basic flame retardant systems: halogen flame retardant system and non-halogen flame retardant system. The halogen-based flame retardant system is usually a bromine-containing flame retardant in combination with antimony trioxide. A large number of studies have shown that a glass fiber reinforced nylon material to which a bromine-based flame retardant is added generates harmful substances such as smoke and hydrogen bromide when burned. Will cause the body to suffocate. Therefore, the development of safety, environmental protection and halogen-free flame retardant systems for glass fiber reinforced nylon has become a research hotspot. In recent years, new halogen-free flame retardants or flame retardant systems for glass fiber reinforced nylon have emerged.

According to reports in the literature, the halogen-free flame retardant applied to glass fiber reinforced mainly includes two basic types of systems: one is red phosphorus; the other is phosphorus-nitrogen flame retardant system. For red phosphorus, although its flame retardant effect is good, it faces two problems: First, the color of red phosphorus limits its application range, usually only applied to black products; second, it is easy to produce phosphine during processing. It is a poisonous substance that brings environmental and safety issues, so red phosphorus is not the best choice for glass reinforced nylon. For the phosphorus-nitrogen flame retardant system, this is a kind of high-efficiency flame retardant system, which has high flame retardant efficiency and avoids some defects of red phosphorus, which is a hot spot of current research.

At present, the most widely used is a phosphorus-nitrogen complex system based on aluminum diethylaluminate, for example, a mixture of aluminum phosphite and a melamine polyphosphate (MPP) system, which has a high phosphorus content. And the synergistic effect of phosphorus and nitrogen, can achieve high-efficiency flame retardant of glass fiber reinforced nylon, there is no product color problem, and has a high decomposition temperature, in the high-temperature processing of glass fiber reinforced nylon, there will be no phosphating Highly toxic gases such as hydrogen. However, for the phosphorus-nitrogen complex system based on aluminum diethylphosphite, there are still some shortcomings, mainly as follows: First, the two components will have a certain reaction decomposition at high temperature, and a small amount of acid gas is generated. These acid gases Corrosion will occur on the metal parts of the processing equipment, and the parts will need to be replaced after a certain period of time, which will bring about an increase in cost and a decrease in production efficiency. Second, there is a certain precipitation of the nitrogen-containing compound MPP, and the material is injected in the injection molding process. After the modulus of the product, there will be deposits on the mold. The presence of these deposits will affect the appearance of the product. At this time, it is necessary to stop the cleaning of the mold, which will also reduce the production efficiency, and this precipitation will also cause the flame retardant to the product. The surface migration leads to uneven distribution and loss of the flame retardant, which ultimately causes the flame retardant of the material to fail, posing a safety hazard.

In general, the flame retardant system currently applied to glass fiber reinforced nylon has problems such as color, toxic gas, easy precipitation and corrosion, some are fatal problems and cannot be used, and some cause cost increase and efficiency decrease. Wait. Therefore, it is necessary to develop a new halogen-free flame retardant system.

Summary of the invention

The invention aims at the defects of the existing phosphorus-nitrogen compound-based flame retardant system based on aluminum diethylphosphite for the glass fiber reinforced nylon material, and discloses a halogen-free flame retardant compounding system for glass fiber reinforced nylon, The halogen-free flame retardant compounding system has the characteristics of high flame retardancy, no migration, non-corrosion equipment, etc., and can be well adapted to the glass fiber reinforced nylon material system, and obtains a halogen-free flame-retardant glass fiber reinforced nylon material with excellent comprehensive performance.

The specific technical solutions are as follows:

A halogen-free flame retardant compounding system for glass fiber reinforced nylon, the raw material composition comprises:

The invention adopts aluminum diethylphosphoric acid phosphate, and cooperates with special high temperature resistant non-migrating aluminum phosphite, melamine metal phosphite and zinc stannate to form a synergistic compound flame retardant system based on phosphorus aluminum nitride structure. It solves the defects that the existing flame retardant system is easy to corrode, easy to migrate and precipitate.

The invention will be described in detail below:

The inventors of the present invention conducted extensive and intensive research for the purpose of solving various defects existing in the halogen-free flame retardant system applied to glass fiber reinforced nylon materials. In view of the existing problems of the flame retardant glass fiber reinforced nylon based on the compound flame retardant system based on diethylaluminum hypoaluminum phosphate, a new flame retardant system was investigated, and it was found that aluminum diethylphosphoric acid synergized with aluminum phosphite and a small amount of melamine. Metal phosphites are a good solution to this problem.

The chemical structure of aluminum diethylphosphinate is shown in the following formula (I):

Aluminum diethylphosphoric acid is characterized by high phosphorus content, good flame retardancy, high initial decomposition temperature, low water solubility, migration resistance and no moisture absorption. Currently, it is widely used in engineering plastics such as nylon and PBT. Especially in glass fiber reinforced engineering plastics. The use of aluminum diethylphosphite alone does not cause precipitation problems, but its flame retardancy is insufficient, so it is also necessary to compound with nitrogen-containing MPP in order to achieve flame retardancy. At present, the flame retardant system applied to glass fiber reinforced nylon is basically a synergistic MPP system with diethylaluminum hypophosphite.

However, when diethylphosphoric acid is used in combination with MPP, its decomposition temperature will decrease, acid gas and ammonia will be released during processing, which will corrode metal parts of processing equipment, and the migration characteristics of MPP will make the mold surface There are deposits that affect the appearance and require regular cleaning of the mold to reduce production efficiency. Obviously, the existence of MPP is the key to causing these problems, to minimize the use of MPP or not to use MPP.

The inventors of the present invention have found through research that in the presence of aluminum diethylphosphinate, a suitable amount of aluminum phosphite is added to form a flame-retardant system mainly composed of a phosphorus-aluminum structure, and the system has good flame retardant properties. The molecular structure of phosphorous acid is shown in the following formula (II):

Aluminum phosphite has a high thermal decomposition temperature, low water solubility, migration resistance; synergistic action with aluminum diethylaluminate to solve the problem of precipitation and deposition in the mold, but the improvement of corrosion resistance is not obvious, and resistance The burning performance is slightly worse than the phosphorus-nitrogen compounding system.

Therefore, after research by the inventors of the present invention, it has been found that the introduction of a small amount of a compound having a basic group which is resistant to high temperature and which does not precipitate, a melamine metal phosphite, can not only solve the problem of corrosion resistance, but also provide Flame retardancy, there is no problem of precipitation.

The melamine metal phosphite has a high decomposition temperature and exhibits a higher pH value in the aqueous solution than the MPP, and its water solubility is also low, and does not migrate and precipitate. Moreover, the system contains nitrogen, which can synergize with the phosphorus-aluminum structure to improve flame retardancy.

Preferably, the melamine metal phosphite is selected from the group consisting of melamine aluminum phosphite and/or melamine calcium phosphite.

For the preparation method of the melamine metal phosphite, refer to the Chinese patent document published as CN 105492520 A, specifically:

The melamine is reacted with the metal phosphite in an aqueous solution, and then heated in the presence of an oxidizing agent at a temperature between 150 and 500 ° C to obtain a solid compound;

The metal phosphite is selected from the group consisting of aluminum phosphite and/or calcium phosphite.

Further, it has been found that the introduction of a small amount of zinc stannate which does not precipitate at a high temperature in the above system can further improve corrosion resistance and provide flame retardancy, and there is no problem of precipitation.

The molecular formula of zinc stannate is: ZnSnO ₃ , which has a high decomposition temperature, low water solubility, and does not migrate and precipitate. It can cooperate with the phosphorus-aluminum structure to improve the flame retardancy, and has a smoke suppressing effect and a reduced smoke density.

Preferably, the aluminum diethyl phosphite has an average particle diameter D50 of 20 to 50 μm; the aluminum phosphite has an average particle diameter D50 of 20 to 50 μm; and the average particle diameter of the melamine metal phosphite. D50 is 20 to 50 μm; and the zinc stannate has an average particle diameter D50 of 20 to 50 μm. Each of the above powder raw materials adopts the same particle size range, and is convenient for uniform mixing of several powders.

The invention also discloses a halogen-free flame-retardant glass fiber reinforced nylon material, which adopts the halogen-free flame-retardant compounding system of the above composition.

Preferably, the halogen-free flame-retardant glass fiber reinforced nylon material comprises, by weight percentage, a raw material composition comprising:

The nylon is selected from at least one of nylon 6, nylon 66, nylon MXD6, and nylon 6T.

The adjuvant includes a lubricant and an antioxidant.

Further preferably, in the halogen-free flame-retardant glass fiber reinforced nylon material, the halogen-free flame-retardant compounding system comprises, by weight percentage, the raw material composition comprises:

The halogen-free flame retardant compounding system accounts for 15 to 20% by weight of the halogen-free flame-retardant glass fiber reinforced nylon material system.

The halogen-free flame-retardant glass fiber reinforced nylon material prepared by the above formula can achieve UL94 V0 (1.6mm) flame retardant grade, and has the advantages of non-corrosive equipment and no precipitation.

The invention also discloses a preparation method of the halogen-free flame-retardant glass fiber reinforced nylon material, which is specifically:

(1) Weighing each component in the halogen-free flame retardant compounding system according to the ratio, and mixing with each auxiliary agent after high-speed stirring to obtain a powder raw material;

(2) Using a twin-screw extruder, after the temperature set in each zone is stabilized, nylon is added from the hopper, and the glass fiber is added through the glass fiber port, and the powder raw material of the step (1) is fed through the powder feeding hole to start. The main machine and the feeder are extruded and granulated to obtain the halogen-free flame-retardant glass fiber reinforced nylon material.

Compared with the prior art, the present invention has the following advantages:

The halogen-free flame-retardant compounding system based on the combination of aluminum diethylaluminate, aluminum phosphite, melamine metal phosphite and zinc stannate provided by the invention has high flame retardant, non-migrating and non-corrosive equipment Advantages; can be well adapted to the glass fiber reinforced nylon material system, the prepared halogen-free flame-retardant glass fiber reinforced nylon material, can achieve UL94 V0 (1.6mm) flame retardant grade, and no precipitation, no corrosion equipment.

Detailed ways

Example 1

The halogen-free flame retardant compounding system is applied to glass fiber reinforced nylon, and the performance of the flame retardant is investigated according to the following steps and test methods.

(1) Mixing of halogen-free flame retardant systems

In the high agitator, the components and other auxiliaries of the compound flame retardant system pre-weighed according to the ratio are added, and the high-speed stirring is started, and the mixture is stirred for 10 minutes to complete the mixing and discharging of the powder.

(2) Extrusion granulation of materials

The temperature of each zone of the twin-screw extruder is set at a predetermined temperature. After the temperature is stabilized for 20 minutes, nylon is added from the hopper, and the glass fiber is added through the glass fiber port, and the powder mixed in the step (1) is fed through the powder feeding hole. Start the main machine and the feeder to complete the extrusion granulation of the material. The granulated material is sent to the silo through the air delivery system and dried.

(3) Application and testing of materials

The dried materials are injected into the injection molding machine to test the standard samples specified in various test standards, and the performance of related materials is tested. Focus on the following performance indicators:

Flame retardant test

Tested according to UL94 V0 test standard.

Migration resistance experiment

The prepared halogen-free flame-retardant glass fiber reinforced nylon sample was placed in a constant temperature and humidity chamber at a temperature of 85 ° C and a relative humidity of 85%, and the state of the surface of the sample after 168 hours was visually observed.

Corrosion experiment

A metal block is arranged on the die, and the high temperature material is contacted with the metal block in the die, and the loss of the metal after granulation of 25 Kg of the material is tested. The higher the loss, the worse the corrosion resistance. Corrosion is considered acceptable if the amount of corrosion is <0.1%.

The materials and ratios in this example are shown in Table 1. The test results of the obtained materials are shown in Table 1.

The preparation method of melamine aluminum phosphite in this embodiment can be found in the patent document CN 105492520 A.

Example 2

The procedure was carried out in the same manner as in Example 1, except that the ratio of aluminum phosphite was maintained, and the ratio of aluminum phosphite, melamine aluminum phosphite and zinc stannate was adjusted. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Example 3

The implementation process was the same as in Example 1, except that the ratio of aluminum diethylaphosphate and aluminum phosphite was adjusted, and the total amount of the flame retardant system was kept constant. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Example 4

The implementation process was the same as in Example 1, except that the ratio of aluminum diethylphosphoric acid and zinc stannate was kept, the ratio of the other two components was adjusted, and the total amount of the flame retardant system was kept constant. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Comparative example 1

The procedure of implementation was the same as in Example 1, except that melamine aluminum phosphite was not used. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Comparative example 2

The procedure was the same as in Example 1, except that aluminum phosphite and melamine aluminum phosphite were not used. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Comparative example 3

The procedure of implementation was the same as in Example 1, except that aluminum phosphite was not used. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Comparative example 4

The procedure was the same as in Example 1, except that only diethylaluminum hypophosphite was used. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Comparative example 5

The procedure was carried out in the same manner as in Example 1, except that aluminum diethylphosphite was used in combination with melamine polyphosphate. Other materials and ratios are shown in Table 1. The results of the materials obtained are shown in Table 1.

Table 1

Claims (10)

A halogen-free flame retardant compounding system for glass fiber reinforced nylon, characterized in that, by weight percentage, the raw material composition comprises:

The halogen-free flame-retardant compounding system for glass-reinforced reinforced nylon according to claim 1, wherein the aluminum diethyl phosphite has an average particle diameter D50 of 20 to 50 μm. The halogen-free flame-retardant compounding system for glass-reinforced reinforced nylon according to claim 1, wherein the aluminum phosphite has an average particle diameter D50 of 20 to 50 μm. The halogen-free flame retardant compounding system for glass fiber reinforced nylon according to claim 1, wherein the melamine metal phosphite is selected from the group consisting of melamine aluminum phosphite and/or trimer. The calcium cyanide phosphite has an average particle diameter D50 of 20 to 50 μm. The halogen-free flame-retardant compounding system for glass-reinforced nylon according to claim 1, wherein the zinc stannate has an average particle diameter D50 of 20 < D50 < 50 μm. A halogen-free flame-retardant glass fiber reinforced nylon material characterized by using the halogen-free flame-retardant compounding system according to any one of claims 1 to 5. The halogen-free flame-retardant glass fiber reinforced nylon material according to claim 6, wherein the raw material composition comprises:

The halogen-free flame-retardant glass fiber reinforced nylon material according to claim 7, wherein the raw material composition of the halogen-free flame-retardant compounding system comprises:

The halogen-free flame-retardant glass fiber reinforced nylon material according to claim 6, wherein the nylon is at least one selected from the group consisting of nylon 6, nylon 66, nylon MXD6, and nylon 6T. The halogen-free flame-retardant glass fiber reinforced nylon material according to claim 6, wherein the auxiliary agent comprises a lubricant and an antioxidant.